How often to water agapanthus in California

In July, established agapanthus in loam needs a deep watering about every 14 days in the Central Valley, about every 7 days on the south coast and about every 6 days in the South Inland zone. Sandy soil holds less water, so waterings come closer together. Clay stretches them. Check the soil before each watering and skip one after a soaking rain.

In July in the Central Valley, established agapanthus needs about 0.1 gallons a day for a plant 2 feet across and about 0.4 gallons a day for a plant 4 feet across. Give it in deep waterings spread days apart rather than a little every day, so the whole root zone gets wet.

Yes. WUCOLS rates agapanthus separately for each of the six California climate zones: moderate water in the North-Central Coastal zone, low water in the Central Valley zone, moderate water in the South Coastal zone, moderate water in the South Inland zone, moderate water in the High and Intermediate Desert zone, moderate water in the Low Desert zone. The monthly table above shows how the same rating translates into different gallon amounts as reference evapotranspiration changes.

Yes. The thick fleshy roots store water, and in soil that never dries they suffocate and rot. Watch for yellowing leaves across the clump, a soft or smelly base, and leaves that pull away with a gentle tug. When in doubt, let the soil dry a little longer before watering again.

Keep the root ball evenly moist through the first summer while roots grow into the surrounding soil. Check the top of the root zone and water whenever it feels dry a couple of inches down. From the second year on, shift to deeper, less frequent soakings and let the fleshy roots do their job.

Drip works very well. Place emitters around the clump rather than at one point so the wide root mass gets even coverage, and move them outward as the clump spreads over the years. Agapanthus also tolerates sprinkler spray, so it fits fine in beds beside a sprayed lawn.

In the ground, usually not. Growth slows in the cool months and winter rain covers the small need in most of the state. Water only during a long dry, warm spell, and keep an eye on containers, which dry faster than garden soil. Deciduous types that die back for winter need even less.

A few yellow outer leaves are normal, since the plant sheds old foliage as new leaves push from the center. Yellowing across the whole clump is different and usually means too much water or poor drainage rather than thirst. Let the soil dry between waterings and make sure the spot drains freely. A thirsty plant looks dull and droopy, not yellow.

Water is only part of the picture. Deep shade, recent division and heavy nitrogen feeding all cut bloom, and a clump that ran bone dry in spring often sends up fewer stalks. Agapanthus actually flowers best when slightly crowded, so resist dividing a healthy clump. Give it sun, steady spring moisture and time, and the stalks return.